You can put some toys in the exhibit, like balls, hoops to swim, buoys...

Place the food in different places of the exhibit: in buoys, pipes, some places of the exhibit, high places... Try to make it not very easy, or the enrichment will not help; or very difficult, or the animal can get stressed.

It is also good not stay in the same always: it is good to present the animal new things that it has never seen before (toys, food, challenges, friends...)

Train the animal to do tricks is also an option, but I'm not a fan of this: what you teach for the animal making it rotate to have food?